1. Field of the Invention
This invention relates to feed supplements and particularly to the manufacture of animal feed supplements comprising condensed whey products.
2. Background of the Art
Whey, a by-product of the cheese manufacturing process, is the aqueous solution remaining after the cheese is separated from the cultured milk. Whey contains various nutrients, including proteins, calcium salts, phosphate salts, and lactose. The large volume of whey that results from cheese manufacture represents a serious disposal problem. Lactose, the main ingredient in whey, causes the major problem of disposing of whey. In particular, whey can not be disposed of as sewage since lactose is a carbohydrate and can be utilized by various undesirable microorganisms for growth.
Whey is an obvious source of nutrients for animals and humans as well as microorganisms. However, it must be condensed by removing water to make it economical for use as a nutrient. For example, it is economically desirable to condense whey to about 40 percent dissolved solids, by weight, to avoid handling and shipping of large amounts of water. The solubility of lactose in water is only about 18 percent, by weight, at 25.degree. C.; therefore there is a problem, for the lactose tends to undesirably sediment out of the condensed whey.
It might appear to be a simple matter (if one desired to obtain useful products by condensing whey) to allow the lactose crystals to precipitate from the condensed whey to recover both a solid lactose and a condensed whey which would not be subject to further lactose sedimentation. Lactose, however, has the tendency to form supersaturated solutions. Therefore unless long standing times can be tolerated, lactose continues to crystallize after the crystals of lactose are filtered from the supersaturated filtrate. The resulting heterogeneous condensed whey product is difficult to handle and as a result the simple removal of water to provide a condensed whey has not found commercial favor.
Condensation of whey and spray drying of the resulting condensate to provide a solid material for use in the food industry has also been attempted. The above noted insolubility of lactose in condensed whey solutions results in sedimentation during condensation and fouling of the heat exchange surfaces of the water removal devices by the sediment.
Many have tried to treat whey by methods other than condensation to recover useful products and avoid the problems of disposal. For example, ultrafiltration has been applied to whey to separate the lower molecular weight materials from the protein with the object being to isolate the fractions of whey and thus obtain more valuable products. The ultrafiltration of whey has been found to be uneconomic.
It has been proposed that, prior to condensation, the lactose in whey be hydrolyzed with mineral acid to yield lower sugars which are more soluble than lactose. However, even though lactose may be efficiently hydrolyzed with acid, the necessary requirements of heat, acid and time makes this process uneconomical.
Enzyme hydrolysis of the lactose to lactic acid or glucose and galactose has been utilized to provide a whey that does not separate upon condensation and storage. This process requires no heat input; however, the cost of the enzyme imparts an unacceptable economic burden on the process.
Finally, the treatment of whey with alkaline materials to either coagulate the proteins or convert the lactose in whey to the more soluble lactulose has been suggested. It is found, however, that the alkaline treatment tends to degrade whey and therefore the product may lose some of its value as a food or nutrient. Recent processes, which utilize alkali treatment in combination with various complexing agents such as aluminates, borates (or boric acid), and/or treatments with trialkylamines (with or without boric acid), have been applied to minimize alkali degradation and optimize conversion of lactose to a more soluble isomer, i.e., lactulose. In each of these processes, however, the reactants utilized in the conversion of lactose to lactulose must be removed from the reaction product prior to use as an animal feed. For example, the boron from the boric acid reactant must be carefully removed because of its poisonous nature. Excessive aluminum also interferes with the proper assimilation of phosphorus, calcium and magnesium by an animal and, therefore, while not poisonous must be removed as well.
Thus it is one object of the invention to provide a whey condensate which does not sediment upon storage for long periods of time and/or at less than ambient temperatures.
It is another object of the invention to provide a whey condensate which does not have to be post treated to remove reactants or reaction products utilized in the solubilization of the lactose contained in the whey.
It is another object of the instant invention to provide a condensed whey which is suitable for blending with other sources of nutrients to provide a full ration animal feed.
It is another object of the invention to provide a condensed whey which is stable to fermentation and spoilage caused by microorganisms while in storage.
It is another object of the invention to provide a condensed whey which is useful for stabilizing blends thereof with other nutrient sources against spoilage.
It is another object of the invention to provide a blend of condensed whey and another source of nutrients having a high moisture content that is stable during storage.
It is another object of the invention to provide a treated whey that can be condensed without sedimentation of lactose therefrom.
Other objects and advantages of the invention will be apparent from the following specification.